From the NY Times:

For now, thanks to psychologists at the University of Texas at Austin, we can at last count the whys. After asking nearly 2,000 people why they’d had sex, the researchers have assembled and categorized a total of 237 reasons — everything from “I wanted to feel closer to God” to “I was drunk.” They even found a few people who claimed to have been motivated by the desire to have a child …

Others said they did it to “help me fall asleep,” “make my partner feel powerful,” “burn calories,” “return a favor,” “keep warm,” “hurt an enemy” or “change the topic of conversation.” The lamest may have been, “It seemed like good exercise,” although there is also this: “Someone dared me.” …

The best news is that both men and women ranked the same reason most often: “I was attracted to the person.”

The rest of the top 10 for each gender were also almost all the same, including “I wanted to express my love for the person,” “I was sexually aroused and wanted the release” and “It’s fun.”

No matter what the reason, men were more likely to cite it than women, with a couple of notable exceptions. Women were more likely to say they had sex because, “I wanted to express my love for the person” and “I realized I was in love.” This jibes with conventional wisdom about women emphasizing the emotional aspects of sex, although it might also reflect the female respondents’ reluctance to admit to less lofty motives.

The results contradicted another stereotype about women: their supposed tendency to use sex to gain status or resources.

“Our findings suggest that men do these things more than women,” Dr. Buss said, alluding to the respondents who said they’d had sex to get things, like a promotion, a raise or a favor. Men were much more likely than women to say they’d had sex to “boost my social status” or because the partner was famous or “usually ‘out of my league.’ ” …

If nothing else, the results seem to be a robust confirmation of the hypothesis in the old joke: How can a woman get a man to take off his clothes? Ask him.

To make sense of the 237 reasons, Dr. Buss and Dr. Meston created a taxonomy with four general categories:

¶Physical: “The person had beautiful eyes” or “a desirable body,” or “was good kisser” or “too physically attractive to resist.” Or “I wanted to achieve an orgasm.”

¶Goal Attainment: “I wanted to even the score with a cheating partner” or “break up a rival’s relationship” or “make money” or “be popular.” Or “because of a bet.”

¶Emotional: “I wanted to communicate at a deeper level” or “lift my partner’s spirits” or “say ‘Thank you.’ ” Or just because “the person was intelligent.”

¶Insecurity: “I felt like it was my duty” or “I wanted to boost my self-esteem” or “It was the only way my partner would spend time with me.”

So if you had this list of all 237 reasons with you on a date and a woman kept turning you down, you could, ahem, whip this out and run down the list, surely finding something the woman would agree with.

However, if that fails, then it will be useful to know this: How Swearing Works:

Most researchers agree that swearing came from early forms of word magic. Studies of modern, non-literate cultures suggest that swearwords came from the belief that spoken words have power. Some cultures, especially ones that have not developed a written language, believe that spoken words can curse or bless people or can otherwise affect the world. This leads to the idea that some words are either very good or very bad….

In the Western, English-speaking world, people from every race, class and level of education swear. In America, 72 percent of men and 58 percent of women swear in public. The same is true for 74 percent of 18 to 34 year olds and 48 percent of people who are over age 55. Numerous language researchers report that men swear more than women, but studies that focus on women’s use of language theorize that women’s swearing is simply more context specific….

Functional magnetic resonance imaging (fMRI) studies have shown that the higher and lower parts of the brain can struggle with each other when a person swears. A New York Times article cites several other studies that involve how a healthy brain processes swearing. For example, the brains of people who pride themselves on being educated respond to slang and “illiterate” phrases the same way they do to swearwords. In addition, in studies in which people must identify the color a word is written in (instead of the word itself), swearwords distract the participants from color recognition. You can also remember swearwords about four times better than other words.

Which I suppose goes a long way towards explaining why I can curse fluently in Cantonese but otherwise all I know is how to ask for a Coke and an ashtray.